Fluorometholone is a drug to be used for medical treatment as an anti-inflammatory steroid and is particularly widely used in the form of eye drops. Since fluorometholone is a drug which is hardly soluble in water, it is practically used in the form of ophthalmic suspensions. Since drugs are not dissolved in ophthalmic suspensions, it is necessary to shake the eye drop bottle in order to redisperse uniformly the settling and aggregating drug when the ophthalmic suspensions are used. Accordingly, a method of facilitating the redispersion is used wherein a nonionic surfactant such as polysorbate 80 is added to the ophthalmic suspensions.
The ophthalmic suspensions of fluorometholone are designed to improve redispersibility of the drug as mentioned above, but it is desirable to improve further the ophthalmic suspensions so that the redispersibility is much elevated and the drug can readily be dispersed uniformly. In the ophthalmic suspensions, it is also likely that the drug having been in a uniform dispersion state in preparation forms aggregates during preservation and the drug does not completely return to the original uniform dispersion state although the eye drops are shaken (irreversible aggregate formation). Accordingly, it is also desirable to improve the ophthalmic suspensions so as to reduce this aggregate formation.